The radar detection of targets in the presence of sea clutter has historically relied heavily upon the radial velocity of targets with respect to the radar platform. This detection is generally done in one of two ways. Specifically, it is done by estimating the relative target Dopplers (such as for STAP) (see J. Ward, “Space-time adaptive processing for airborne radar,” MIT Lincoln Laboratory Technical Report ESC-TR-94-109, December 1994). Further, it is also done by examining the path that a target traverses from scan to scan, otherwise known as the “track-before-detect” or “track-to-detect” approach (see B. D. Carlson, E. D. Evans, and S. L. Wilson, “Search radar detection and track with the Hough transform, Part I: System Concept,” IEEE Trans. AES, Vol. 30, no. 1, pp. 102-108, Jan. 1994; B. D. Carlson, E. D. Evans, and S. L. Wilson, “Search radar detection and track with the Hough transform, Part II: detection statistics,” IEEE Trans. AES, Vol. 30, no. 1, pp. 109-115, January 1994; and B. D. Carlson, E. D. Evans, and S. L. Wilson, “Search radar detection and track with the Hough transform, Part IIII: detection performance with binary integration,” IEEE Trans. AES, Vol. 30, no. 1, pp. 116-125, January 1994).
While these approaches can be quite effective in some situations, for targets with little to no radial velocity component, it is quite difficult to differentiate actual targets from the surrounding sea clutter. The reason for this is that a target with low radial velocity with respect to the radar platform has a Doppler frequency close to zero and hence is difficult to distinguish from the background sea clutter. Further, from scan to scan, the target does not appear to be moving so that conventional track-to-detect approaches do no work well either.